Flame retardant (FR) polymers and polymer blends, for example blends with UL V0 and 5V A and B Underwriters Laboratories flammability ratings, are widely prepared and used, especially in a wide variety of electrical and electronic applications. Conversely, only a very limited set of polymers and polymer blends are used in aircraft and other transportation applications, particularly interior parts. All of these applications have stringent flammability safety requirements that the polymer or polymer blend must meet. Particular requirements include smoke density, flame spread, and heat release values. In the United States, Federal Aviation Regulation (FAR) Part 25.853 sets forth the airworthiness standards for aircraft compartment interiors. The safety standards for aircraft and transportation systems used in the United States include a smoke density test specified in FAR 25.5 Appendix F, Part V Amdt 25-116. Flammability requirements include the heat release rate standard described in FAR F25.4 (FAR Section 25, Appendix F, Part IV). Smoke density requirements can be evaluated according to ASTM E-662, ASTM F-814, Airbus ABD0031 and Boeing BSS 7239. In the event of a fire, components made from materials having a low heat release rate, low peak heat release and low smoke density can increase the amount of time available for escape and provide for better visibility during a fire.
In view of the current interior material safety standards, and in anticipation of more stringent standards in the future, materials that exceed governmental and aircraft manufacturer flame safety requirements are sought. Such materials should also advantageously maintain excellent physical and rheological properties, such melt volume rate, melt stability and tensile modulus.